"pertaining to, characterized by, or of the nature of onomatopoeia," 1835, from French onomatopoéique or else from onomatopoeia + -ic. Other adjectival forms include onomatopoeial; onomatopoetic (1827); onomatopoeous (1660s).
onomatopoeic words are imitative of noises
onnagata
onomastic
onomastics
onomatology
onomatopoeia
onomatopoeic
Onondaga
onrush
onset
on-site
onslaught